HTC magnet-on-a-stick tackles touchscreen writing

A new HTC patent application points to a novel way of combining capacitive touchscreens with stylus use — putting a magnetic head on the stylus.

The system, described in US Patent Application 20090167727, attempts to tackle the same problem that RIM addressed with its hybrid resistive/capacitive touchscreen design — that a resistive screen with a stylus allows for handwriting and the selection of tiny icons, but a capacitive screen is faster and more sensitive and allows for multitouch.

RIM's solution is a resistive screen — comprising two layers that feed into a controller when they touch — that has the outer layer coated in a conductive material. HTC's take, however, is to have the stylus provide a charge that is recognisable to the screen in a similar way to how such screens recognise finger-based input.

This is done by using a magnetic head on the stylus:

When a relative speed exists between the stylus and the capacitive touch panel, an inducting current is generated on the capacitive touch panel, and the capacitive touch can calculate the position where the inducting current is generated according to the inducting current. Thus, the stylus can control the capacitive touch panel. In addition, the head of the stylus is smaller than fingers, so the stylus does not shield the sight of the user, and thus smaller icons are also applicable.

The stylus approach should be cheaper to implement than RIM's new screen, but it also introduces the possibility of losing the magnet-on-a-stick.

Both ideas are currently just patent applications, so it may be a long time before we see either system put into practice — if that ever happens.